While the SR-71 Blackbird would ultimately surpass its predecessor’s altitude and speed records, the YF-12 would retain its status as the heftiest, largest, and quickest manned interceptor to ever fly the skies.
The A-12 Avenger II, once envisioned as the U.S. Navy's premier carrier-based stealth bomber, ultimately became a symbol of procurement failure due to excessive cost overruns, technical difficulties, and strategic misalignments.